Sam's Blog

Moving to Spacemacs for Scala and Python

Sam Ritchie -

I've just finished retooling my development environment, and the process was annoying enough that I thought I'd write it up here, for myself in the future, and for you in the present.

tl;dr; I ended up porting my old Emacs config, based on the literate emacs24-starter-kit, over to Spacemacs, and ended up with a great Scala and Python setup.

Read on for the details.

Goals

I've been an Emacs user since my first days with Clojure, and I'm hooked, fully in love. Those Clojure days were a long time ago; as I've spent more time developing in Scala and Python, I've made do with basically just code formatting and syntax highlighting, delegating to an external build tool like SBT in a terminal window to give me compilation feedback every so often. My Emacs config is crusty and old, and way out of date.

I've been working on ScalaRL (github page, microsite), a functional, monadic reinforcement learning framework in Scala, and I've been feeling the pain of my setup. It was time for an overhaul.

I had two goals this weekend:

  • Upgrade my Emacs config to support Metals, the latest and greatest (and only!) Emacs... IDE? out there today.
  • Understand the absolutely insane world of Python packaging well enough that I could dig into some of the latest deep learning examples out there in a reproducible way, more similar to the self-contained Clojure and Scala projects I'm used to.

Spacemacs

Reading about modern Emacs configs it became clear that my old strategy of just manually installing packages that seemed nice had led me into a hellish, non-reproducible setup. I decided to declare bankruptcy and start again with Spacemacs.

Spacemacs is a batteries-and-steroids-included configuration for Emacs designed to lure you into a modal style of editing, like Vim provides. It also provides a large number of community-provided "layers", which are declarative bundles of packages and config hooks designed to add support for different features and languages to Spacemacs.

The Scala layer for Spacemacs looked great, and had support for Metals, a Scala language server designed to give IDE-like functionality to a bunch of different editors. (Ensime is dead! Long live Ensime!)

The Python mode looked great too.

Installation

Here's what I did to install Spacemacs:

First, I went through my .bashrc file and culled out all of the old crap that had accumulated over multiple jobs and many years of building up an environment. The biggest thing I did was to delete any reference to Macports from my machine and my path. The multiple-installation ecosystem for Ruby and Python has always been a pain for me; I suspect that's due to a Linux environment that I built up over years without really knowing what was going on under the hood.

Next, I moved my old $USER/.emacs.d directory to $USER/emacs.d.old so I could reference its settings, and as backup in case I botched what came next.

I deleted my old emacs installation with brew uninstall emacs and killed my alias in /Applications/Emacs.app, then reinstalled the latest and greatest Emacs with the instructions in the Spacemacs beginner's tutorial.

  • First, install Homebrew.
  • Run these two commands:
brew tap d12frosted/emacs-plus
brew install emacs-plus
# brew linkapps emacs-plus

The final, commented-out command won't work anymore, since Homebrew no longer has a linkapps subcommand. Instead, run this to create a symlink in your Applications directory:

ln -s /usr/local/opt/emacs-plus/Emacs.app /Applications

To install Spacemacs itself, run the following commands:

git clone https://github.com/syl20bnr/spacemacs ~/.emacs.d
cd ~/.emacs.d
git checkout 3e93dec6635bf54fa8a36ac8da6d6b98a9775541

This will get Spacemacs up to the revision I used in my configuration, which I know works great for Scala and Python development with my spacemacs.d config.

If you want the fresh Spacemacs experience, you can go ahead and launch Emacs.app by double-clicking the new icon in your /Applications folder and following the rest of the beginner's tutorial here.

Read on for more details about my specific configuration. I'm still using Spacemacs in "holy-mode", or Emacs mode, ie, without the Vim keybindings. I'll work on that next.

Configuring Spacemacs

Here's my old Emacs config directory, based on the emacs24-starter-kit and now almost a decade old.

Spacemacs completely commandeers .emacs.d; instead of writing config there, you get to play in either a .spacemacs file or a .spacemacs.d directory. Either way, Spacemacs generates a big template config for you that you can modify as you get started.

I did the latter, and once I got everything converted I pushed the whole directory to Github. It lives at https://github.com/sritchie/spacemacs.d.

Most of my configuration changes were keybindings that I wanted to keep from my old setup. Here are some examples.

This remaps the Apple command key to Meta, and the option key to super.

(setq mac-option-modifier 'super)
(setq mac-command-modifier 'meta)

This snippet removes the titlebar, making the installation look super smooth:

(add-to-list 'default-frame-alist '(ns-transparent-titlebar . t))

I also installed the Source Code Pro font that Spacemacs prefers. It does look good!

You can check out the Spacemacs dotfile configuration page for more tips. I didn't change too much about the default setup; I was focused on customizing the Scala and Python experiences, as I'll go into next.

Here's my init.el file if you want to peruse the whole range of defaults that you can tweak.

I stuffed all of my language-specific configuration, and the layers I decided to install, into my own layers, which you can find here.

I didn't quite finish; I still have a bunch of Clojure, Lisp and Haskell code to convert over. I'm going to wait to do that until I have the pleasure of programming in those languages again for a project. Until then I'm keeping the org files that used to generate my customizations in this "random" folder in the spacemacs directory.

Python and Scala

I'm going to save the details of customizing Spacemacs for these two development environments for two further posts. I'll link them here when they're complete. Stay tuned!